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Oldest Antarctic Whale Found; Shows Fast Evolution

The oldest known Antarctic whale is seen in an artist's reconstruction.

Illustration courtesy Marcelo Reguero via AFP/Getty Images

The oldest known whale to ply the Antarctic has been found, scientists say.

A 24-inch-long (60-centimeter-long) jawbone was recently discovered amid a rich deposit of fossils on the Antarctic Peninsula (map).

The creature, which may have reached lengths of up to 20 feet (6 meters), had a mouthful of teeth and likely feasted on giant penguins, sharks, and big bony fish, whose remains were also discovered with the jawbone.

The early whale swam polar waters during the Eocene period, some 49 million years ago. Its age suggests fully aquatic whales evolved from their mammalian ancestors more rapidly than previously thought, said researcher Thomas Mörs, paleozoologist at the Swedish Museum of Natural History.

Based on 53-million-year-old fossils of whale-like, semi-aquatic mammals, scientists had thought mammals gave rise to whales in a process that took 15 million years. The new find suggests it took just 4 million years. (See a prehistoric time line.)

What's more, "as soon as they became fully marine animals, they dispersed all over the world, showing the great success of the whale construction," Mörs said in an email.